In the OSNR model for EDFA amplifiers, SNR OUT = 1/(1/SNR IN + FhvB/P IN ), what does SNR IN represent?（）

A . practice B . production C . presentation D . preparation

A . made；is sailing B . has made；is sailing C . made；sails D . has made；sail

A .  the signal to noise of the current optical amplifier B .  the signal to noise of the previous amplifier or source C .  the signal to noise introduced by the optical multiplexer D .  the accumulated noise to signal ratio of the optical channel

A . best-effort delivery B . ingress committed rate （ICR） C . shaping and policing D . egress committed rate （ECR） E . Integrated Services （IntServ） F . differentiated services （DiffServ）

A . Layer one B . Layer two C . Layer three D . Layer four

A . Applicationlayer B . Presentationlayer C . Sessionlayer D . Transportlayer E . Networklayer F . Datalinklayer G . Physicallayer

A . transport B . network C . presentation D . session E . applicatio

A . Machine signature B . Customer number C . Site location D . Customer contact number

A . It encourages industry standardization by defining what functions occur at each layer of the model. B . It necessitates changes in functionality in one layer to other layers. C . It enables equipment efficiency from different vendors to use the same electronic components. D . It divides the network communication process into smaller and simpler components, thus aiding component development, design, and troubleshooting. E . It supports the evolution of multiple competing standards, and thus enhances business equipment manufacturing opportunities.

A . practice B . production C . presentation D . preparation

A . session B . physical C . protocol D . gateway E . data link F . transport G . applicatio

A . The gateway voice-capable device is configured to support call control directly performing call setup， call maintenance， and call teardown B . The gateway voice-capable device has a local call routing table configured through a routing protocol. C . The gateway voice-capable device relies on a call agent to support call control. D . The gateway voice-capable device relies on a gatekeeper to support call setup， call maintenance， and call teardown.

A . delay sensitive packets are given preferential treatment B . the default policy identifies a delay sensitive class and default class C . the default policy identifies a delay sensitive class， best effort class， and default class D . the model is highly scalable E . the model is still predominant on the internet F the model provides guaranteed service

A . Classdiagram B . Componentdiagram C . Sequencediagram D . Use case diagram

A.different activities B.different project size C.different project management manner D.different way of activity organization

A．Applicationlayer B．Presentationlayer C．Sessionlayer D．Transportlayer E．Networklayer F．DatalinklayerG.Physicallayer

是 否

A．This is to foster eating disorder among the models. B．Clothes looks better on thin models. C．This is to be deliberately different from normal women. 此题为多项选择题。